STENBERG, Warren. On Weak Separation of Convex Sets and on $\alpha$-Ubiquitous Sets. MATHEMATICA SCANDINAVICA, [S. l.], v. 16, p. 55–74, 1965. DOI: 10.7146/math.scand.a-10748. Disponível em: https://tidsskrift.dk/math/article/view/10748. Acesso em: 14 aug. 2026.